Generally, an integrated circuit (“IC”) is a circuit in which all or some of the circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible. An IC is commonly embodied in a wafer. A wafer can be a slice or flat disk, of semiconductor material or, for example, of semiconductor material deposited on a substrate, in which circuits or devices are simultaneously processed and, if there is more than one device, subsequently separated into dies. The wafer can have logic circuitry that forms a high speed digital circuit, such as digital logic for a digital phase locked loop (“PLL”) circuit, for example. A digital controlled ring oscillator (“DCO”) is a component of the PLL circuit that facilitates clock generation in a wide range of application-specific integrated circuits (ASICs) including, but not limited to, network controllers, I/O controllers, graphics processors, or the like. As such, the DCO covers a wide frequency range from about 1 GHz to about 4 GHz for varying process, voltage, and temperature (PVT), and also has a fine resolution, such as about 0.5 MHz per least significant bit (LSB).
Having a wide frequency range and maintaining a fine resolution can be difficult in that the resolution is inversely proportional to the frequency step. For example, when the resolution is 0.5 MHz, the mean number of frequency steps is approximately 6000. As such, the DCO has 6000 devices, such as tri-state inverters, that cause the dimensions of the DCO to be over 300 μm×300 μm. The connection wire for 6000 tri-state inverters can be over approximately 500 μm, which results in a relatively large wire capacitance that is over approximately 200 fF. Such a high capacitance can prevent current consumption and prevent the DCO from obtaining optimal or maximum speeds. The two-dimensional (2D) layout for the devices, such as the tri-state inverters, can also inhibit current consumption and prevent the DCO from obtaining optimal or maximum speeds.